The present invention relates generally to apparatus and methods for treating septal defects, and more particularly to apparatus and methods for closing a patent foramen ovale or other septal defect that include a flap of tissue using a needle device.
During development of a fetus in utero, blood is generally oxygenated by the mother""s placenta, not the fetus"" developing lungs. Most of the fetus"" circulation is shunted away from the lungs through specialized vessels or foramens that are open during fetal life, but generally close shortly after birth. Occasionally, however, these foramen fail to close and create hemodynamic problems, which may ultimately prove fatal unless treated.
One defect that may occur is a patent foramen ovale (xe2x80x9cPFOxe2x80x9d) or patent ductus arteriosus (xe2x80x9cPDAxe2x80x9d), which may occur between the left and right atria of the heart. During fetal life, an opening called the foramen ovale allows blood to pass directly from the right atrium to the left atrium (bypassing the lungs). Thus, oxygenated blood from the placenta may travel through the vena cava into the right atrium, through the foramen ovale into the left atrium, and from there into the left ventricle for delivery via the aorta to the fetus"" body. After birth, the foramen ovale is replaced with a membrane called the fossa ovalis, and over time, a solid mass of tissue may form.
Occasionally, this membrane and tissue mass fail to form or completely close the foramen ovale, which may be fatal if untreated. Similar defects may occur in other regions within a septum between chambers of the heart, such as atrial septal defects, ventricular septal defects, and the like.
To close such defects, open surgery may be performed to ligate and close the defect. Such procedures are obviously highly invasive and pose substantial morbidity and mortality risks.
Alternatively, catheter-based procedures have been suggested. These may involve introducing umbrella-like structures into the heart that include opposing expandable structures connected by a hub. One of the expandable structures is inserted through the defect, and both are expanded to secure the tissue surrounding the defect between the structures in an attempt to seal and close the defect. Such structures, however, involve frame structures that support membranes, both of which may fail during the life of the patient being treated, opening the defect, and/or releasing segments of the structure within the patient""s heart.
Accordingly, apparatus and methods for closing patent foramen ovale, patent ductus arteriosus, or other septal defects would be considered useful.
The present invention is directed to apparatus and methods for closing patent foramen ovale (xe2x80x9cPFOxe2x80x9d), patent ductus arteriosus (xe2x80x9cPDAxe2x80x9d), or other septal defects.
In accordance with a first aspect of the present invention, an apparatus for closing a septal defect is provided that includes an elongate needle including a first end defining a tissue-penetrating tip, and a second end defining a substantially blunt tip. A filament extends from an intermediate portion of the needle between the first and second ends, and a locking element, such as a clip, clamp, cross-brace, and the like, may be securable to the filament, thereby preventing the locking element from moving along the filament away from the needle.
Preferably, the needle has a tapered cross-section such that the second end is substantially larger than the first end. A slot may be provided in the needle that extends from the intermediate portion to the second end, the slot having a size for receiving a portion of the filament therein. The second end of the needle may include a flared outer edge and/or a rounded inner edge.
In one embodiment, the locking element may be a clip that is slidable along the filament towards the needle, the clip including opposing arms having teeth or other engaging elements for preventing the clip from being moved along the filament away from the needle. Alternatively, the clip may be plastically deformable such that the clip may received around the filament and then crimped or otherwise secured to the filament during closure of a septal defect, as explained further below.
In accordance with another aspect of the present invention, a delivery apparatus for delivering a needle apparatus, such as that described above, is provided that includes an outer catheter and a pusher member that are slidably coupled to one another. The catheter may be a tubular member including proximal and distal ends and a lumen therebetween, the distal end having a size for insertion into a blood vessel or other body lumen. The needle may be carried within the lumen such that the first end is disposed distally to the second end.
The pusher member may be an inner catheter or other elongate member that is disposed within the lumen of the outer catheter. The pusher member may include a distal end that may be disposed proximate the second end of the needle, the pusher member being movable axially relative to the tubular member for ejecting the needle distally from the lumen. The pusher member may include a lumen extending proximally from the distal end of the pusher member such that the filament extending from the needle may be received through the lumen.
An actuator may be provided on the proximal end of the tubular member and/or the pusher member for advancing the pusher member relative to the tubular member. Preferably, the actuator may limit advancement of the pusher member such that the distal end of the pusher member extends only a predetermined distance beyond the distal end of the tubular member when activated. The actuator may also be coupled to the filament received through the lumen in the pusher member for applying proximal tension to the filament during use, as described further below.
The lumen of the catheter may include an enlarged distal region proximate the distal end for receiving the needle therein. For example, the second end of the needle may have a cross-section that is substantially larger than a cross-section of the distal end of the pusher member. In addition, the second end of the needle may have a flared outer edge such that the second end extends laterally from the distal end of the pusher member. Alternatively, the second end of the needle may simply be larger in cross-section than the distal end of the pusher member, In addition, the second end of the needle may include a rounded edge for facilitating pivoting of the needle about the intermediate region when the filament is pulled proximally.
In addition, the delivery apparatus may include a clip carrier having a proximal end and a distal end having a size for introduction into a body lumen. A clip or other locking element may be releasably carried by the distal end of the clip carrier, the clip including opposing arms defining a slot therebetween for receiving a filament therein. The clip carrier may include a hammer/anvil arrangement for plastically deforming at least one of the opposing arms to engage a filament received within the slot. The clip carrier may be completely separate from the catheter and pusher member or may be carried by the catheter and/or pusher member. For example, the catheter may include an additional lumen through which the clip carrier may be advanced.
In a further alternative, the delivery apparatus may include an imaging device including an imaging element associated with the distal end of the tubular member for imaging beyond the distal end of the tubular member. For example, the imaging device may be an endoscope or ultrasound device that may be received within a lumen of the tubular member or may be a separate device that may introduced independently into the patient but used in conjunction with the delivery apparatus during a procedure.
In accordance with yet another aspect of the present invention, a method is provided for closing a PFO or other septal defect within a patient""s heart. Generally, the septal defect includes a flap of tissue partially detached from a septum wall between first and second chambers of the heart, the flap of tissue and surrounding tissue of the septum wall defining a septal opening through the septum wall. Initially, a needle may be provided that includes a first end defining a tissue-penetrating tip, a second end defining a substantially blunt tip, and an intermediate portion between the first and second ends from which a filament extends.
The needle may be advanced through the patient""s vasculature until the needle is disposed within the first chamber of the heart adjacent the septal opening. For example, the needle may be disposed within a distal end of a delivery apparatus including a catheter and a pusher member slidably coupled to one another. The distal end of the delivery apparatus may be advanced through the patient""s vasculature, e.g., from a percutaneous entry site, into the first chamber until the distal end is disposed adjacent the flap of tissue.
The first end of the needle may be directed through the flap of tissue until the second end passes through the flap of tissue and the needle is disposed within the second chamber of the heart. For example, the pusher member may be advanced distally relative to the catheter, thereby directing the needle from within the delivery apparatus and into and through the flap of tissue. Preferably, the pusher member is advanced a predetermined distance, e.g., such that the distal end of the pusher member extends completely through the flap of tissue to ensure that the needle is directed entirely into the second chamber.
The filament may then be pulled proximally, thereby causing the needle to pivot about the intermediate region such that the first and second ends of the needle straddle the septal opening within the second chamber. As the filament is pulled, the blunt tip of the needle may engage a distal surface of the flap of tissue, thereby preventing the needle from being pulled back through the flap of tissue. The blunt tip of the needle may include an enlarged or flared end, e.g., larger than the distal end of the pusher member, also to prevent the needle from being pulled through the flap of tissue. Instead, the blunt tip of the needle may slide along a distal surface of the flap of tissue and/or the septum wall, thereby causing the needle to pivot about the intermediate region of the needle. Preferably, the blunt tip of the needle includes a rounded inner edge for facilitating movement of the needle along the distal surface.
The flap of tissue may be directed into engagement with the septum wall to at least partially close the septal opening. For example, a locking element may be secured to the filament, the locking element engaging the proximal surface of the flap of tissue to secure the flap of tissue between the needle and the locking element. To accomplish this, a clip carrier may be introduced into the first chamber of the heart. The clip carrier may be manipulated to receive the filament within a clip carried by the clip carrier, and then the clip may be crimped or otherwise plastically deformed, e.g., by a mechanical crimper on the clip carrier, to secure the clip to the filament. Alternatively, a locking element may be slidably secured on the filament. The locking element may be slid along the filament towards the needle until the flap of tissue is secured against the tissue surrounding the septal opening. The locking element may include teeth or other elements that accommodate sliding the locking element along the filament towards the needle, but prevent subsequent movement of the locking element along the filament away from the needle. In addition, the needle and/or locking element may have lengths greater than a width of the septal opening, such that the flap of tissue may be secured between the needle and the locking element, thereby substantially closing the septal opening. The filament may be cut or otherwise detached from the delivery apparatus, and the delivery apparatus removed from the patient""s body.
In accordance with still another aspect of the present invention, an apparatus is provided that includes an elongate needle including a first end defining a tissue-penetrating tip, a second end defining a substantially blunt tip, and a longitudinal axis extending between the first and second ends. A filament extends from an intermediate portion of the needle between the first and second ends. At least a segment of the filament may be biased towards a configuration defining a plane extending generally parallel to the longitudinal axis. Thus, the filament may be extendable towards a generally linear configuration, but may resiliently attempt to return towards the planar configuration.
In a preferred embodiment, the filament includes first and second segments. The first segment may be attached to the intermediate portion of the needle and biased to extend transversely with respect to the longitudinal axis. The second segment extends from the first segment and may be biased to extend transversely to the first segment such that the second segment defines the plane that extends generally parallel to the longitudinal axis of the needle. The second segment may be biased towards a coiled configuration, the coiled configuration lying substantially within the plane. Alternatively, the second segment may be biased towards other planar configurations lying substantially within the plane, for example, including at least one of an xe2x80x9cL,xe2x80x9d a xe2x80x9cU,xe2x80x9d a xe2x80x9cY,xe2x80x9d and/or an xe2x80x9cSxe2x80x9d shape.
The apparatus may include a tubular member, including proximal and distal ends and a lumen extending therebetween. The distal end may have a size for insertion into a blood vessel. Generally, the needle is carried within the lumen such that the first end is disposed distally to the second end. A pusher member may be slidably disposed within the lumen, the pusher member including a distal end disposed proximate the second end of the needle. Preferably, the pusher member is movable axially relative to the tubular member for ejecting the needle distally from the lumen.
The pusher member and/or the tubular member may include a gripping mechanism for releasably securing a loose end of the filament, thereby restraining the filament in the generally linear configuration. An actuator may also be provided on the proximal end of the pusher member and/or the tubular member for releasing the loose end of the filament, whereupon the filament may be free to assume the planar configuration.
The apparatus may be used for closing a septal defect within a patient""s heart, similar to the embodiment described above. The needle may be advanced through the patient""s vasculature, e.g., within the tubular member, until the needle is disposed within the first chamber of the heart adjacent the septal opening. The first end of the needle may be directed through the flap of tissue until the second end passes through the flap of tissue and the needle is disposed within the second chamber of the heart. The filament may be pulled, thereby causing the needle to pivot about the intermediate region such that the first and second ends of the needle straddle the septal opening within the second chamber. The filament may then be released, the filament resiliently assuming a generally planar configuration, thereby engaging the flap of tissue between the needle and the filament to at least partially close the septal opening.
Other objects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings.